The behavior of a two element segmented capped monopole antenna is described in terms of three natural resonances of the antenna structure. A numerical eigenmode solver is used to derive the resonant frequency and quality factor of the natural resonances, as well as the impedance properties of these modes when excited individually. Analyzing the antenna in terms of its natural resonant modes provides physical insights into both its behavior and the fundamental limitations of its performance.

When designing an antenna to occupy a volume with dimensions small relative to the wavelength, one of the primary challenges is optimizing the bandwidth. Analyzing the behavior of two-, four-, and six-arm small multielement spherical antennas provides physical insight into the multiresonant impedance behavior of these antennas, clearly illustrating their ultimate performance limits and yielding ideas for improved designs. The analysis can be applied towards understanding the behavior of other multielement antenna structures as well.

Multiscale representations of images have become a standard tool in image analysis. Such representations offer a number of advantages over fixed-scale methods, including the potential for improved performance in denoising, compression, and the ability to represent distinct but complementary information that exists at various scales.

Wireless geolocation - or position determination - may be accomplished via many different techniques, including Received Signal Strength (RSS). RSS techniques are interesting for their simplicity and generality, and can be accomplished from a set of reference stations radiating any set of waveforms. This motivates the idea of performing RSS-type positioning from a set of Signals-of-Opportunity (SoO) that happen to be in a local area (e.g. commercial radio, TV sources, etc.).

Wireless geolocation (position determination) may be accomplished via many techniques. RSS techniques are interesting due to their simplicity and generality, and can be accomplished from a set of reference stations radiating any set of waveforms. This motivates the idea of performing RSS-type positioning from a set of Signals-of-Opportunity (SoO) that happen to be in a local area (e.g. commercial radio, TV sources, etc.). The large number of potential sources helps improve the location accuracy.

There has been much research devoted to determining lower bounds on the quality factor of antennas. This paper explains simple general expressions for the lower bounds on the quality factor (Q) of electric- and magnetic-dipole antennas, in arbitrarily shaped electrically small volumes, excited by general sources and by global electric-current sources alone.

A study of the effect of surrounding electrically small, top-loaded, electric-dipole antennas with a thin shell of high-permeability magnetic material. The magnetic polarization currents induced in the thin shell of magnetic material reduce the internal stored energy, resulting in a lower Q as compared to conventional designs.

Presidential Executive Order 13407 has mandated the creation of an integrated public alert and warning system (IPAWS) to inform the public during periods of national emergency. This will ensure that under all conditions the President can rapidly and effectively address and warn the public over a broad range of communications devices and under any emergency condition (FEMA/DHS has set a goal to alert 85% of the population within a 10 minute time frame). This paper demonstrates Alerting Penetration Models, which allow estimation of the impacts from deployment of various alerting systems: Radio, TV, Internet, and Cell Phone.

Estimating network parameters from noisy data is a hard problem that can be made even more difficult by the presence of a malicious adversary who may corrupt the measurement process by capturing a trusted node or perturbing data externally. The adversary may have complete knowledge of the networking protocols that rely on the parameter estimates and may adjust its effect on the system to push protocols into incorrect operating regimes.

LGS is applying 4G technology to enable mobile access to cloud services and enhance situational awareness for the USG. Our 4G solutions offer secure wireless access through value-added services while leveraging commercial infrastructure and components with carrier grade redundancy to deliver mission critical services and applications. By transforming the government’s ability to securely send and receive information of all kinds — anywhere, at any time, on any device — LGS contributes to mission success, from protecting the homeland to increasing service to the citizen.

The tactical edge is filled with rich content, providing real-time intelligence and situation awareness to the warfighter. The current network architecture lacks support for lateral sharing of this critical content. Content is currently accessed from known servers and may require reach-back over bandwidth-constrained links. In this work we present SCALE, a Scalable Content-centric Architecture ensuring Locality and Efficiency.

We demonstrate logic functionalities in a high-speed all-optical logic circuit based on differential MachZehnder interferometers with semiconductor optical amplifiers as the nonlinear optical elements. The circuit, implemented by hybrid integration of the semiconductor optical amplifiers on a planar lightwave circuit platform fabricated in silica glass, can be flexibly configured to realize a variety of Boolean logic gates. We present both simulations and experimental demonstrations of cascaded alloptical operations for 80-Gb/s on-off keyed data.

We demonstrate a record receiver sensitivity of 2.7 photons per bit at 6.23-Gb/s net data rate using PDM-QPSK with 4-ary-pulse-position-modulation. This signal is transmitted over a 370-km unrepeatered ultra-large-area-fiber span with 71.7-dB total loss budget.

The U.S. Government’s voice and data networks continue to provide high quality telecommunications and data services. The voice switching systems, including End Office (Class 5) Switches and Private Branch Exchanges (PBXs), meet the U.S. Government switching requirements and provide high quality, secure, high availability communications. These Time Division Multiplexed (TDM) switching systems continue to be a viable solution for U.S. Government networks.

The consideration of content-centric networking as a fundamental driver for mobile ad-hoc network (MANET) protocol design, including systematic evaluation of the suitability and effectiveness of existing approaches toward designing a content-centric MANET.

Network bandwidth demand continues to grow within U.S. Government Agencies due to the use of collaboration, sophisticated IP services, and multimedia applications. Agencies can meet this demand by offering 100G IP/MPLS networking services at the WAN edge. Alcatel-Lucent was the first to deliver 100 Gigabit interfaces for IP/ MPLS Edge Services, doing so with the development of the innovative FP2 chipset, the industry’s first 100G network processor (NPU) silicon. Alcatel-Lucent raised the performance bar again with the introduction of the FP3 chipset this year. Each generation of the FP chipset provides advances in power efficiency, supplied bandwidth, scalability, and innovative network services. This whitepaper discusses these FP chipset advances and the resulting benefits to Federal Government agencies.

A penetration test is a method of evaluating the security of a target by simulating an attack. Because multi-step attacks are often the most effective way for an attacker to compromise a system or network, we consider the problem of automatically designing a penetration test to remotely evaluate the security of a target computer or network device.

The study of electrically small radiofrequency (RF) antenna elements is of both practical and fundamental importance. From a practical standpoint, emerging applications such multi-input multi-output (MIMO) mobile communications systems and RF-tagging benefit from the ability to make antenna size smaller. In this paper, we consider the use of materials with negative electric permittivity as a building block for constructing effective small antenna elements. Although such materials do not occur naturally at microwave frequencies, negative permittivity can be realized at microwave frequencies using plasmas of the appropriate charge density.

Transmitting sources may be located by estimating the angles-of-arrival at a receiving array if the “direct path” is present, (i.e, the straight line path between source and destination). Angle-of-arrival estimation may be efficiently performed by well-known approaches such as MUSIC and ESPRIT, which are one-dimensional angle estimation methods. Yet many real-world applications require a two-dimensional angle-of-arrival estimation because the sources and receive array may not lie in a single plane.

When exploring alternatives to the patch antenna, it is important to compare not only the performance of the full antenna designs, but also the physical properties of the resonant modes of the alternative structures directly with those of the patch. This paper studies a periodically structured surface resonator that is used to provide a wider bandwidth alternative to a simple patch antenna with a thickness of less than 1/30 of a wavelength. The bandwidth improvement results, in part, because the resonator has a fundamental radiation mode with a lower radiation Q-factor than the simple patch of the same electrical volume.